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                  <h1>backbone.js</h1>
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              <pre><code>Backbone.js 1.1.0

(c) 2010-2011 Jeremy Ashkenas, DocumentCloud Inc.
(c) 2011-2013 Jeremy Ashkenas, DocumentCloud and Investigative Reporters &amp; Editors
Backbone may be freely distributed under the MIT license.
For all details and documentation:
http://backbonejs.org</code></pre>

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            <div class="content"><div class='highlight'><pre>(<span class="keyword">function</span>(){</pre></div></div>
            
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              <h2>Initial Setup</h2>

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              <p>Save a reference to the global object (<code>window</code> in the browser, <code>exports</code>
on the server).</p>

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            <div class="content"><div class='highlight'><pre>  <span class="keyword">var</span> root = <span class="keyword">this</span>;</pre></div></div>
            
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              <p>Save the previous value of the <code>Backbone</code> variable, so that it can be
restored later on, if <code>noConflict</code> is used.</p>

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            <div class="content"><div class='highlight'><pre>  <span class="keyword">var</span> previousBackbone = root.Backbone;</pre></div></div>
            
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              <p>Create local references to array methods we&#39;ll want to use later.</p>

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            <div class="content"><div class='highlight'><pre>  <span class="keyword">var</span> array = [];
  <span class="keyword">var</span> push = array.push;
  <span class="keyword">var</span> slice = array.slice;
  <span class="keyword">var</span> splice = array.splice;</pre></div></div>
            
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              <p>The top-level namespace. All public Backbone classes and modules will
be attached to this. Exported for both the browser and the server.</p>

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            <div class="content"><div class='highlight'><pre>  <span class="keyword">var</span> Backbone;
  <span class="keyword">if</span> (<span class="keyword">typeof</span> exports !== <span class="string">'undefined'</span>) {
    Backbone = exports;
  } <span class="keyword">else</span> {
    Backbone = root.Backbone = {};
  }</pre></div></div>
            
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              <p>Current version of the library. Keep in sync with <code>package.json</code>.</p>

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            <div class="content"><div class='highlight'><pre>  Backbone.VERSION = <span class="string">'1.1.0'</span>;</pre></div></div>
            
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              <p>Require Underscore, if we&#39;re on the server, and it&#39;s not already present.</p>

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            <div class="content"><div class='highlight'><pre>  <span class="keyword">var</span> _ = root._;
  <span class="keyword">if</span> (!_ &amp;&amp; (<span class="keyword">typeof</span> require !== <span class="string">'undefined'</span>)) _ = require(<span class="string">'underscore'</span>);</pre></div></div>
            
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              <p>For Backbone&#39;s purposes, jQuery, Zepto, Ender, or My Library (kidding) owns
the <code>$</code> variable.</p>

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            <div class="content"><div class='highlight'><pre>  Backbone.$ = root.jQuery || root.Zepto || root.ender || root.$;</pre></div></div>
            
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              <p>Runs Backbone.js in <em>noConflict</em> mode, returning the <code>Backbone</code> variable
to its previous owner. Returns a reference to this Backbone object.</p>

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            <div class="content"><div class='highlight'><pre>  Backbone.noConflict = <span class="keyword">function</span>() {
    root.Backbone = previousBackbone;
    <span class="keyword">return</span> <span class="keyword">this</span>;
  };</pre></div></div>
            
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              <p>Turn on <code>emulateHTTP</code> to support legacy HTTP servers. Setting this option
will fake <code>&quot;PATCH&quot;</code>, <code>&quot;PUT&quot;</code> and <code>&quot;DELETE&quot;</code> requests via the <code>_method</code> parameter and
set a <code>X-Http-Method-Override</code> header.</p>

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            <div class="content"><div class='highlight'><pre>  Backbone.emulateHTTP = <span class="literal">false</span>;</pre></div></div>
            
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              <p>Turn on <code>emulateJSON</code> to support legacy servers that can&#39;t deal with direct
<code>application/json</code> requests ... will encode the body as
<code>application/x-www-form-urlencoded</code> instead and will send the model in a
form param named <code>model</code>.</p>

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            <div class="content"><div class='highlight'><pre>  Backbone.emulateJSON = <span class="literal">false</span>;</pre></div></div>
            
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              <h2>Backbone.Events</h2>

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              <p>A module that can be mixed in to <em>any object</em> in order to provide it with
custom events. You may bind with <code>on</code> or remove with <code>off</code> callback
functions to an event; <code>trigger</code>-ing an event fires all callbacks in
succession.</p>
<pre><code>var object = {};
_.extend(object, Backbone.Events);
object.on(&#39;expand&#39;, function(){ alert(&#39;expanded&#39;); });
object.trigger(&#39;expand&#39;);</code></pre>

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            <div class="content"><div class='highlight'><pre>  <span class="keyword">var</span> Events = Backbone.Events = {</pre></div></div>
            
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              <p>Bind an event to a <code>callback</code> function. Passing <code>&quot;all&quot;</code> will bind
the callback to all events fired.</p>

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            <div class="content"><div class='highlight'><pre>    on: <span class="keyword">function</span>(name, callback, context) {
      <span class="keyword">if</span> (!eventsApi(<span class="keyword">this</span>, <span class="string">'on'</span>, name, [callback, context]) || !callback) <span class="keyword">return</span> <span class="keyword">this</span>;
      <span class="keyword">this</span>._events || (<span class="keyword">this</span>._events = {});
      <span class="keyword">var</span> events = <span class="keyword">this</span>._events[name] || (<span class="keyword">this</span>._events[name] = []);
      events.push({callback: callback, context: context, ctx: context || <span class="keyword">this</span>});
      <span class="keyword">return</span> <span class="keyword">this</span>;
    },</pre></div></div>
            
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              <p>Bind an event to only be triggered a single time. After the first time
the callback is invoked, it will be removed.</p>

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            <div class="content"><div class='highlight'><pre>    once: <span class="keyword">function</span>(name, callback, context) {
      <span class="keyword">if</span> (!eventsApi(<span class="keyword">this</span>, <span class="string">'once'</span>, name, [callback, context]) || !callback) <span class="keyword">return</span> <span class="keyword">this</span>;
      <span class="keyword">var</span> self = <span class="keyword">this</span>;
      <span class="keyword">var</span> once = _.once(<span class="keyword">function</span>() {
        self.off(name, once);
        callback.apply(<span class="keyword">this</span>, arguments);
      });
      once._callback = callback;
      <span class="keyword">return</span> <span class="keyword">this</span>.on(name, once, context);
    },</pre></div></div>
            
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              <p>Remove one or many callbacks. If <code>context</code> is null, removes all
callbacks with that function. If <code>callback</code> is null, removes all
callbacks for the event. If <code>name</code> is null, removes all bound
callbacks for all events.</p>

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            <div class="content"><div class='highlight'><pre>    off: <span class="keyword">function</span>(name, callback, context) {
      <span class="keyword">var</span> retain, ev, events, names, i, l, j, k;
      <span class="keyword">if</span> (!<span class="keyword">this</span>._events || !eventsApi(<span class="keyword">this</span>, <span class="string">'off'</span>, name, [callback, context])) <span class="keyword">return</span> <span class="keyword">this</span>;
      <span class="keyword">if</span> (!name &amp;&amp; !callback &amp;&amp; !context) {
        <span class="keyword">this</span>._events = {};
        <span class="keyword">return</span> <span class="keyword">this</span>;
      }
      names = name ? [name] : _.keys(<span class="keyword">this</span>._events);
      <span class="keyword">for</span> (i = <span class="number">0</span>, l = names.length; i &lt; l; i++) {
        name = names[i];
        <span class="keyword">if</span> (events = <span class="keyword">this</span>._events[name]) {
          <span class="keyword">this</span>._events[name] = retain = [];
          <span class="keyword">if</span> (callback || context) {
            <span class="keyword">for</span> (j = <span class="number">0</span>, k = events.length; j &lt; k; j++) {
              ev = events[j];
              <span class="keyword">if</span> ((callback &amp;&amp; callback !== ev.callback &amp;&amp; callback !== ev.callback._callback) ||
                  (context &amp;&amp; context !== ev.context)) {
                retain.push(ev);
              }
            }
          }
          <span class="keyword">if</span> (!retain.length) <span class="keyword">delete</span> <span class="keyword">this</span>._events[name];
        }
      }

      <span class="keyword">return</span> <span class="keyword">this</span>;
    },</pre></div></div>
            
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              <p>Trigger one or many events, firing all bound callbacks. Callbacks are
passed the same arguments as <code>trigger</code> is, apart from the event name
(unless you&#39;re listening on <code>&quot;all&quot;</code>, which will cause your callback to
receive the true name of the event as the first argument).</p>

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            <div class="content"><div class='highlight'><pre>    trigger: <span class="keyword">function</span>(name) {
      <span class="keyword">if</span> (!<span class="keyword">this</span>._events) <span class="keyword">return</span> <span class="keyword">this</span>;
      <span class="keyword">var</span> args = slice.call(arguments, <span class="number">1</span>);
      <span class="keyword">if</span> (!eventsApi(<span class="keyword">this</span>, <span class="string">'trigger'</span>, name, args)) <span class="keyword">return</span> <span class="keyword">this</span>;
      <span class="keyword">var</span> events = <span class="keyword">this</span>._events[name];
      <span class="keyword">var</span> allEvents = <span class="keyword">this</span>._events.all;
      <span class="keyword">if</span> (events) triggerEvents(events, args);
      <span class="keyword">if</span> (allEvents) triggerEvents(allEvents, arguments);
      <span class="keyword">return</span> <span class="keyword">this</span>;
    },</pre></div></div>
            
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              <p>Tell this object to stop listening to either specific events ... or
to every object it&#39;s currently listening to.</p>

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            <div class="content"><div class='highlight'><pre>    stopListening: <span class="keyword">function</span>(obj, name, callback) {
      <span class="keyword">var</span> listeningTo = <span class="keyword">this</span>._listeningTo;
      <span class="keyword">if</span> (!listeningTo) <span class="keyword">return</span> <span class="keyword">this</span>;
      <span class="keyword">var</span> remove = !name &amp;&amp; !callback;
      <span class="keyword">if</span> (!callback &amp;&amp; <span class="keyword">typeof</span> name === <span class="string">'object'</span>) callback = <span class="keyword">this</span>;
      <span class="keyword">if</span> (obj) (listeningTo = {})[obj._listenId] = obj;
      <span class="keyword">for</span> (<span class="keyword">var</span> id <span class="keyword">in</span> listeningTo) {
        obj = listeningTo[id];
        obj.off(name, callback, <span class="keyword">this</span>);
        <span class="keyword">if</span> (remove || _.isEmpty(obj._events)) <span class="keyword">delete</span> <span class="keyword">this</span>._listeningTo[id];
      }
      <span class="keyword">return</span> <span class="keyword">this</span>;
    }

  };</pre></div></div>
            
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              <p>Regular expression used to split event strings.</p>

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            <div class="content"><div class='highlight'><pre>  <span class="keyword">var</span> eventSplitter = <span class="regexp">/\s+/</span>;</pre></div></div>
            
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              <p>Implement fancy features of the Events API such as multiple event
names <code>&quot;change blur&quot;</code> and jQuery-style event maps <code>{change: action}</code>
in terms of the existing API.</p>

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            <div class="content"><div class='highlight'><pre>  <span class="keyword">var</span> eventsApi = <span class="keyword">function</span>(obj, action, name, rest) {
    <span class="keyword">if</span> (!name) <span class="keyword">return</span> <span class="literal">true</span>;</pre></div></div>
            
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              <p>Handle event maps.</p>

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            <div class="content"><div class='highlight'><pre>    <span class="keyword">if</span> (<span class="keyword">typeof</span> name === <span class="string">'object'</span>) {
      <span class="keyword">for</span> (<span class="keyword">var</span> key <span class="keyword">in</span> name) {
        obj[action].apply(obj, [key, name[key]].concat(rest));
      }
      <span class="keyword">return</span> <span class="literal">false</span>;
    }</pre></div></div>
            
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              <p>Handle space separated event names.</p>

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            <div class="content"><div class='highlight'><pre>    <span class="keyword">if</span> (eventSplitter.test(name)) {
      <span class="keyword">var</span> names = name.split(eventSplitter);
      <span class="keyword">for</span> (<span class="keyword">var</span> i = <span class="number">0</span>, l = names.length; i &lt; l; i++) {
        obj[action].apply(obj, [names[i]].concat(rest));
      }
      <span class="keyword">return</span> <span class="literal">false</span>;
    }

    <span class="keyword">return</span> <span class="literal">true</span>;
  };</pre></div></div>
            
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              <p>A difficult-to-believe, but optimized internal dispatch function for
triggering events. Tries to keep the usual cases speedy (most internal
Backbone events have 3 arguments).</p>

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            <div class="content"><div class='highlight'><pre>  <span class="keyword">var</span> triggerEvents = <span class="keyword">function</span>(events, args) {
    <span class="keyword">var</span> ev, i = -<span class="number">1</span>, l = events.length, a1 = args[<span class="number">0</span>], a2 = args[<span class="number">1</span>], a3 = args[<span class="number">2</span>];
    <span class="keyword">switch</span> (args.length) {
      <span class="keyword">case</span> <span class="number">0</span>: <span class="keyword">while</span> (++i &lt; l) (ev = events[i]).callback.call(ev.ctx); <span class="keyword">return</span>;
      <span class="keyword">case</span> <span class="number">1</span>: <span class="keyword">while</span> (++i &lt; l) (ev = events[i]).callback.call(ev.ctx, a1); <span class="keyword">return</span>;
      <span class="keyword">case</span> <span class="number">2</span>: <span class="keyword">while</span> (++i &lt; l) (ev = events[i]).callback.call(ev.ctx, a1, a2); <span class="keyword">return</span>;
      <span class="keyword">case</span> <span class="number">3</span>: <span class="keyword">while</span> (++i &lt; l) (ev = events[i]).callback.call(ev.ctx, a1, a2, a3); <span class="keyword">return</span>;
      <span class="keyword">default</span>: <span class="keyword">while</span> (++i &lt; l) (ev = events[i]).callback.apply(ev.ctx, args);
    }
  };

  <span class="keyword">var</span> listenMethods = {listenTo: <span class="string">'on'</span>, listenToOnce: <span class="string">'once'</span>};</pre></div></div>
            
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              <p>Inversion-of-control versions of <code>on</code> and <code>once</code>. Tell <em>this</em> object to
listen to an event in another object ... keeping track of what it&#39;s
listening to.</p>

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            <div class="content"><div class='highlight'><pre>  _.each(listenMethods, <span class="keyword">function</span>(implementation, method) {
    Events[method] = <span class="keyword">function</span>(obj, name, callback) {
      <span class="keyword">var</span> listeningTo = <span class="keyword">this</span>._listeningTo || (<span class="keyword">this</span>._listeningTo = {});
      <span class="keyword">var</span> id = obj._listenId || (obj._listenId = _.uniqueId(<span class="string">'l'</span>));
      listeningTo[id] = obj;
      <span class="keyword">if</span> (!callback &amp;&amp; <span class="keyword">typeof</span> name === <span class="string">'object'</span>) callback = <span class="keyword">this</span>;
      obj[implementation](name, callback, <span class="keyword">this</span>);
      <span class="keyword">return</span> <span class="keyword">this</span>;
    };
  });</pre></div></div>
            
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              <p>Aliases for backwards compatibility.</p>

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            <div class="content"><div class='highlight'><pre>  Events.bind   = Events.on;
  Events.unbind = Events.off;</pre></div></div>
            
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              <p>Allow the <code>Backbone</code> object to serve as a global event bus, for folks who
want global &quot;pubsub&quot; in a convenient place.</p>

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            <div class="content"><div class='highlight'><pre>  _.extend(Backbone, Events);</pre></div></div>
            
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              <h2>Backbone.Model</h2>

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              <p>Backbone <strong>Models</strong> are the basic data object in the framework --
frequently representing a row in a table in a database on your server.
A discrete chunk of data and a bunch of useful, related methods for
performing computations and transformations on that data.</p>
<p>Create a new model with the specified attributes. A client id (<code>cid</code>)
is automatically generated and assigned for you.</p>

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            <div class="content"><div class='highlight'><pre>  <span class="keyword">var</span> Model = Backbone.Model = <span class="keyword">function</span>(attributes, options) {
    <span class="keyword">var</span> attrs = attributes || {};
    options || (options = {});
    <span class="keyword">this</span>.cid = _.uniqueId(<span class="string">'c'</span>);
    <span class="keyword">this</span>.attributes = {};
    <span class="keyword">if</span> (options.collection) <span class="keyword">this</span>.collection = options.collection;
    <span class="keyword">if</span> (options.parse) attrs = <span class="keyword">this</span>.parse(attrs, options) || {};
    attrs = _.defaults({}, attrs, _.result(<span class="keyword">this</span>, <span class="string">'defaults'</span>));
    <span class="keyword">this</span>.set(attrs, options);
    <span class="keyword">this</span>.changed = {};
    <span class="keyword">this</span>.initialize.apply(<span class="keyword">this</span>, arguments);
  };</pre></div></div>
            
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              <p>Attach all inheritable methods to the Model prototype.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>  _.extend(Model.prototype, Events, {</pre></div></div>
            
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              <p>A hash of attributes whose current and previous value differ.</p>

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            <div class="content"><div class='highlight'><pre>    changed: <span class="literal">null</span>,</pre></div></div>
            
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              <p>The value returned during the last failed validation.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    validationError: <span class="literal">null</span>,</pre></div></div>
            
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              <p>The default name for the JSON <code>id</code> attribute is <code>&quot;id&quot;</code>. MongoDB and
CouchDB users may want to set this to <code>&quot;_id&quot;</code>.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    idAttribute: <span class="string">'id'</span>,</pre></div></div>
            
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              <p>Initialize is an empty function by default. Override it with your own
initialization logic.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    initialize: <span class="keyword">function</span>(){},</pre></div></div>
            
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              <p>Return a copy of the model&#39;s <code>attributes</code> object.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    toJSON: <span class="keyword">function</span>(options) {
      <span class="keyword">return</span> _.clone(<span class="keyword">this</span>.attributes);
    },</pre></div></div>
            
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              <p>Proxy <code>Backbone.sync</code> by default -- but override this if you need
custom syncing semantics for <em>this</em> particular model.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    sync: <span class="keyword">function</span>() {
      <span class="keyword">return</span> Backbone.sync.apply(<span class="keyword">this</span>, arguments);
    },</pre></div></div>
            
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              <p>Get the value of an attribute.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    get: <span class="keyword">function</span>(attr) {
      <span class="keyword">return</span> <span class="keyword">this</span>.attributes[attr];
    },</pre></div></div>
            
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              <p>Get the HTML-escaped value of an attribute.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    escape: <span class="keyword">function</span>(attr) {
      <span class="keyword">return</span> _.escape(<span class="keyword">this</span>.get(attr));
    },</pre></div></div>
            
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              <p>Returns <code>true</code> if the attribute contains a value that is not null
or undefined.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    has: <span class="keyword">function</span>(attr) {
      <span class="keyword">return</span> <span class="keyword">this</span>.get(attr) != <span class="literal">null</span>;
    },</pre></div></div>
            
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              <p>Set a hash of model attributes on the object, firing <code>&quot;change&quot;</code>. This is
the core primitive operation of a model, updating the data and notifying
anyone who needs to know about the change in state. The heart of the beast.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    set: <span class="keyword">function</span>(key, val, options) {
      <span class="keyword">var</span> attr, attrs, unset, changes, silent, changing, prev, current;
      <span class="keyword">if</span> (key == <span class="literal">null</span>) <span class="keyword">return</span> <span class="keyword">this</span>;</pre></div></div>
            
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              <p>Handle both <code>&quot;key&quot;, value</code> and <code>{key: value}</code> -style arguments.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>      <span class="keyword">if</span> (<span class="keyword">typeof</span> key === <span class="string">'object'</span>) {
        attrs = key;
        options = val;
      } <span class="keyword">else</span> {
        (attrs = {})[key] = val;
      }

      options || (options = {});</pre></div></div>
            
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              <p>Run validation.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>      <span class="keyword">if</span> (!<span class="keyword">this</span>._validate(attrs, options)) <span class="keyword">return</span> <span class="literal">false</span>;</pre></div></div>
            
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              <p>Extract attributes and options.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>      unset           = options.unset;
      silent          = options.silent;
      changes         = [];
      changing        = <span class="keyword">this</span>._changing;
      <span class="keyword">this</span>._changing  = <span class="literal">true</span>;

      <span class="keyword">if</span> (!changing) {
        <span class="keyword">this</span>._previousAttributes = _.clone(<span class="keyword">this</span>.attributes);
        <span class="keyword">this</span>.changed = {};
      }
      current = <span class="keyword">this</span>.attributes, prev = <span class="keyword">this</span>._previousAttributes;</pre></div></div>
            
        </li>
        
        
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              <p>Check for changes of <code>id</code>.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>      <span class="keyword">if</span> (<span class="keyword">this</span>.idAttribute <span class="keyword">in</span> attrs) <span class="keyword">this</span>.id = attrs[<span class="keyword">this</span>.idAttribute];</pre></div></div>
            
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              <p>For each <code>set</code> attribute, update or delete the current value.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>      <span class="keyword">for</span> (attr <span class="keyword">in</span> attrs) {
        val = attrs[attr];
        <span class="keyword">if</span> (!_.isEqual(current[attr], val)) changes.push(attr);
        <span class="keyword">if</span> (!_.isEqual(prev[attr], val)) {
          <span class="keyword">this</span>.changed[attr] = val;
        } <span class="keyword">else</span> {
          <span class="keyword">delete</span> <span class="keyword">this</span>.changed[attr];
        }
        unset ? <span class="keyword">delete</span> current[attr] : current[attr] = val;
      }</pre></div></div>
            
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              <p>Trigger all relevant attribute changes.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>      <span class="keyword">if</span> (!silent) {
        <span class="keyword">if</span> (changes.length) <span class="keyword">this</span>._pending = <span class="literal">true</span>;
        <span class="keyword">for</span> (<span class="keyword">var</span> i = <span class="number">0</span>, l = changes.length; i &lt; l; i++) {
          <span class="keyword">this</span>.trigger(<span class="string">'change:'</span> + changes[i], <span class="keyword">this</span>, current[changes[i]], options);
        }
      }</pre></div></div>
            
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              <p>You might be wondering why there&#39;s a <code>while</code> loop here. Changes can
be recursively nested within <code>&quot;change&quot;</code> events.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>      <span class="keyword">if</span> (changing) <span class="keyword">return</span> <span class="keyword">this</span>;
      <span class="keyword">if</span> (!silent) {
        <span class="keyword">while</span> (<span class="keyword">this</span>._pending) {
          <span class="keyword">this</span>._pending = <span class="literal">false</span>;
          <span class="keyword">this</span>.trigger(<span class="string">'change'</span>, <span class="keyword">this</span>, options);
        }
      }
      <span class="keyword">this</span>._pending = <span class="literal">false</span>;
      <span class="keyword">this</span>._changing = <span class="literal">false</span>;
      <span class="keyword">return</span> <span class="keyword">this</span>;
    },</pre></div></div>
            
        </li>
        
        
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              <p>Remove an attribute from the model, firing <code>&quot;change&quot;</code>. <code>unset</code> is a noop
if the attribute doesn&#39;t exist.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    unset: <span class="keyword">function</span>(attr, options) {
      <span class="keyword">return</span> <span class="keyword">this</span>.set(attr, <span class="keyword">void</span> <span class="number">0</span>, _.extend({}, options, {unset: <span class="literal">true</span>}));
    },</pre></div></div>
            
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              <p>Clear all attributes on the model, firing <code>&quot;change&quot;</code>.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    clear: <span class="keyword">function</span>(options) {
      <span class="keyword">var</span> attrs = {};
      <span class="keyword">for</span> (<span class="keyword">var</span> key <span class="keyword">in</span> <span class="keyword">this</span>.attributes) attrs[key] = <span class="keyword">void</span> <span class="number">0</span>;
      <span class="keyword">return</span> <span class="keyword">this</span>.set(attrs, _.extend({}, options, {unset: <span class="literal">true</span>}));
    },</pre></div></div>
            
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              <p>Determine if the model has changed since the last <code>&quot;change&quot;</code> event.
If you specify an attribute name, determine if that attribute has changed.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    hasChanged: <span class="keyword">function</span>(attr) {
      <span class="keyword">if</span> (attr == <span class="literal">null</span>) <span class="keyword">return</span> !_.isEmpty(<span class="keyword">this</span>.changed);
      <span class="keyword">return</span> _.has(<span class="keyword">this</span>.changed, attr);
    },</pre></div></div>
            
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              <p>Return an object containing all the attributes that have changed, or
false if there are no changed attributes. Useful for determining what
parts of a view need to be updated and/or what attributes need to be
persisted to the server. Unset attributes will be set to undefined.
You can also pass an attributes object to diff against the model,
determining if there <em>would be</em> a change.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    changedAttributes: <span class="keyword">function</span>(diff) {
      <span class="keyword">if</span> (!diff) <span class="keyword">return</span> <span class="keyword">this</span>.hasChanged() ? _.clone(<span class="keyword">this</span>.changed) : <span class="literal">false</span>;
      <span class="keyword">var</span> val, changed = <span class="literal">false</span>;
      <span class="keyword">var</span> old = <span class="keyword">this</span>._changing ? <span class="keyword">this</span>._previousAttributes : <span class="keyword">this</span>.attributes;
      <span class="keyword">for</span> (<span class="keyword">var</span> attr <span class="keyword">in</span> diff) {
        <span class="keyword">if</span> (_.isEqual(old[attr], (val = diff[attr]))) <span class="keyword">continue</span>;
        (changed || (changed = {}))[attr] = val;
      }
      <span class="keyword">return</span> changed;
    },</pre></div></div>
            
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              <p>Get the previous value of an attribute, recorded at the time the last
<code>&quot;change&quot;</code> event was fired.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    previous: <span class="keyword">function</span>(attr) {
      <span class="keyword">if</span> (attr == <span class="literal">null</span> || !<span class="keyword">this</span>._previousAttributes) <span class="keyword">return</span> <span class="literal">null</span>;
      <span class="keyword">return</span> <span class="keyword">this</span>._previousAttributes[attr];
    },</pre></div></div>
            
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              <p>Get all of the attributes of the model at the time of the previous
<code>&quot;change&quot;</code> event.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    previousAttributes: <span class="keyword">function</span>() {
      <span class="keyword">return</span> _.clone(<span class="keyword">this</span>._previousAttributes);
    },</pre></div></div>
            
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              <p>Fetch the model from the server. If the server&#39;s representation of the
model differs from its current attributes, they will be overridden,
triggering a <code>&quot;change&quot;</code> event.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    fetch: <span class="keyword">function</span>(options) {
      options = options ? _.clone(options) : {};
      <span class="keyword">if</span> (options.parse === <span class="keyword">void</span> <span class="number">0</span>) options.parse = <span class="literal">true</span>;
      <span class="keyword">var</span> model = <span class="keyword">this</span>;
      <span class="keyword">var</span> success = options.success;
      options.success = <span class="keyword">function</span>(resp) {
        <span class="keyword">if</span> (!model.set(model.parse(resp, options), options)) <span class="keyword">return</span> <span class="literal">false</span>;
        <span class="keyword">if</span> (success) success(model, resp, options);
        model.trigger(<span class="string">'sync'</span>, model, resp, options);
      };
      wrapError(<span class="keyword">this</span>, options);
      <span class="keyword">return</span> <span class="keyword">this</span>.sync(<span class="string">'read'</span>, <span class="keyword">this</span>, options);
    },</pre></div></div>
            
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              <p>Set a hash of model attributes, and sync the model to the server.
If the server returns an attributes hash that differs, the model&#39;s
state will be <code>set</code> again.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    save: <span class="keyword">function</span>(key, val, options) {
      <span class="keyword">var</span> attrs, method, xhr, attributes = <span class="keyword">this</span>.attributes;</pre></div></div>
            
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              <p>Handle both <code>&quot;key&quot;, value</code> and <code>{key: value}</code> -style arguments.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>      <span class="keyword">if</span> (key == <span class="literal">null</span> || <span class="keyword">typeof</span> key === <span class="string">'object'</span>) {
        attrs = key;
        options = val;
      } <span class="keyword">else</span> {
        (attrs = {})[key] = val;
      }

      options = _.extend({validate: <span class="literal">true</span>}, options);</pre></div></div>
            
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              <p>If we&#39;re not waiting and attributes exist, save acts as
<code>set(attr).save(null, opts)</code> with validation. Otherwise, check if
the model will be valid when the attributes, if any, are set.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>      <span class="keyword">if</span> (attrs &amp;&amp; !options.wait) {
        <span class="keyword">if</span> (!<span class="keyword">this</span>.set(attrs, options)) <span class="keyword">return</span> <span class="literal">false</span>;
      } <span class="keyword">else</span> {
        <span class="keyword">if</span> (!<span class="keyword">this</span>._validate(attrs, options)) <span class="keyword">return</span> <span class="literal">false</span>;
      }</pre></div></div>
            
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              <p>Set temporary attributes if <code>{wait: true}</code>.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>      <span class="keyword">if</span> (attrs &amp;&amp; options.wait) {
        <span class="keyword">this</span>.attributes = _.extend({}, attributes, attrs);
      }</pre></div></div>
            
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              <p>After a successful server-side save, the client is (optionally)
updated with the server-side state.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>      <span class="keyword">if</span> (options.parse === <span class="keyword">void</span> <span class="number">0</span>) options.parse = <span class="literal">true</span>;
      <span class="keyword">var</span> model = <span class="keyword">this</span>;
      <span class="keyword">var</span> success = options.success;
      options.success = <span class="keyword">function</span>(resp) {</pre></div></div>
            
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              <p>Ensure attributes are restored during synchronous saves.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>        model.attributes = attributes;
        <span class="keyword">var</span> serverAttrs = model.parse(resp, options);
        <span class="keyword">if</span> (options.wait) serverAttrs = _.extend(attrs || {}, serverAttrs);
        <span class="keyword">if</span> (_.isObject(serverAttrs) &amp;&amp; !model.set(serverAttrs, options)) {
          <span class="keyword">return</span> <span class="literal">false</span>;
        }
        <span class="keyword">if</span> (success) success(model, resp, options);
        model.trigger(<span class="string">'sync'</span>, model, resp, options);
      };
      wrapError(<span class="keyword">this</span>, options);

      method = <span class="keyword">this</span>.isNew() ? <span class="string">'create'</span> : (options.patch ? <span class="string">'patch'</span> : <span class="string">'update'</span>);
      <span class="keyword">if</span> (method === <span class="string">'patch'</span>) options.attrs = attrs;
      xhr = <span class="keyword">this</span>.sync(method, <span class="keyword">this</span>, options);</pre></div></div>
            
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              <p>Restore attributes.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>      <span class="keyword">if</span> (attrs &amp;&amp; options.wait) <span class="keyword">this</span>.attributes = attributes;

      <span class="keyword">return</span> xhr;
    },</pre></div></div>
            
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              <p>Destroy this model on the server if it was already persisted.
Optimistically removes the model from its collection, if it has one.
If <code>wait: true</code> is passed, waits for the server to respond before removal.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    destroy: <span class="keyword">function</span>(options) {
      options = options ? _.clone(options) : {};
      <span class="keyword">var</span> model = <span class="keyword">this</span>;
      <span class="keyword">var</span> success = options.success;

      <span class="keyword">var</span> destroy = <span class="keyword">function</span>() {
        model.trigger(<span class="string">'destroy'</span>, model, model.collection, options);
      };

      options.success = <span class="keyword">function</span>(resp) {
        <span class="keyword">if</span> (options.wait || model.isNew()) destroy();
        <span class="keyword">if</span> (success) success(model, resp, options);
        <span class="keyword">if</span> (!model.isNew()) model.trigger(<span class="string">'sync'</span>, model, resp, options);
      };

      <span class="keyword">if</span> (<span class="keyword">this</span>.isNew()) {
        options.success();
        <span class="keyword">return</span> <span class="literal">false</span>;
      }
      wrapError(<span class="keyword">this</span>, options);

      <span class="keyword">var</span> xhr = <span class="keyword">this</span>.sync(<span class="string">'delete'</span>, <span class="keyword">this</span>, options);
      <span class="keyword">if</span> (!options.wait) destroy();
      <span class="keyword">return</span> xhr;
    },</pre></div></div>
            
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              <p>Default URL for the model&#39;s representation on the server -- if you&#39;re
using Backbone&#39;s restful methods, override this to change the endpoint
that will be called.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    url: <span class="keyword">function</span>() {
      <span class="keyword">var</span> base = _.result(<span class="keyword">this</span>, <span class="string">'urlRoot'</span>) || _.result(<span class="keyword">this</span>.collection, <span class="string">'url'</span>) || urlError();
      <span class="keyword">if</span> (<span class="keyword">this</span>.isNew()) <span class="keyword">return</span> base;
      <span class="keyword">return</span> base + (base.charAt(base.length - <span class="number">1</span>) === <span class="string">'/'</span> ? <span class="string">''</span> : <span class="string">'/'</span>) + encodeURIComponent(<span class="keyword">this</span>.id);
    },</pre></div></div>
            
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              <p><strong>parse</strong> converts a response into the hash of attributes to be <code>set</code> on
the model. The default implementation is just to pass the response along.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    parse: <span class="keyword">function</span>(resp, options) {
      <span class="keyword">return</span> resp;
    },</pre></div></div>
            
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              <p>Create a new model with identical attributes to this one.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    clone: <span class="keyword">function</span>() {
      <span class="keyword">return</span> <span class="keyword">new</span> <span class="keyword">this</span>.constructor(<span class="keyword">this</span>.attributes);
    },</pre></div></div>
            
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              <p>A model is new if it has never been saved to the server, and lacks an id.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    isNew: <span class="keyword">function</span>() {
      <span class="keyword">return</span> <span class="keyword">this</span>.id == <span class="literal">null</span>;
    },</pre></div></div>
            
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              <p>Check if the model is currently in a valid state.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    isValid: <span class="keyword">function</span>(options) {
      <span class="keyword">return</span> <span class="keyword">this</span>._validate({}, _.extend(options || {}, { validate: <span class="literal">true</span> }));
    },</pre></div></div>
            
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              <p>Run validation against the next complete set of model attributes,
returning <code>true</code> if all is well. Otherwise, fire an <code>&quot;invalid&quot;</code> event.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    _validate: <span class="keyword">function</span>(attrs, options) {
      <span class="keyword">if</span> (!options.validate || !<span class="keyword">this</span>.validate) <span class="keyword">return</span> <span class="literal">true</span>;
      attrs = _.extend({}, <span class="keyword">this</span>.attributes, attrs);
      <span class="keyword">var</span> error = <span class="keyword">this</span>.validationError = <span class="keyword">this</span>.validate(attrs, options) || <span class="literal">null</span>;
      <span class="keyword">if</span> (!error) <span class="keyword">return</span> <span class="literal">true</span>;
      <span class="keyword">this</span>.trigger(<span class="string">'invalid'</span>, <span class="keyword">this</span>, error, _.extend(options, {validationError: error}));
      <span class="keyword">return</span> <span class="literal">false</span>;
    }

  });</pre></div></div>
            
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              <p>Underscore methods that we want to implement on the Model.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>  <span class="keyword">var</span> modelMethods = [<span class="string">'keys'</span>, <span class="string">'values'</span>, <span class="string">'pairs'</span>, <span class="string">'invert'</span>, <span class="string">'pick'</span>, <span class="string">'omit'</span>];</pre></div></div>
            
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              <p>Mix in each Underscore method as a proxy to <code>Model#attributes</code>.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>  _.each(modelMethods, <span class="keyword">function</span>(method) {
    Model.prototype[method] = <span class="keyword">function</span>() {
      <span class="keyword">var</span> args = slice.call(arguments);
      args.unshift(<span class="keyword">this</span>.attributes);
      <span class="keyword">return</span> _[method].apply(_, args);
    };
  });</pre></div></div>
            
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              </div>
              <h2>Backbone.Collection</h2>

            </div>
            
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              <p>If models tend to represent a single row of data, a Backbone Collection is
more analagous to a table full of data ... or a small slice or page of that
table, or a collection of rows that belong together for a particular reason
-- all of the messages in this particular folder, all of the documents
belonging to this particular author, and so on. Collections maintain
indexes of their models, both in order, and for lookup by <code>id</code>.</p>
<p>Create a new <strong>Collection</strong>, perhaps to contain a specific type of <code>model</code>.
If a <code>comparator</code> is specified, the Collection will maintain
its models in sort order, as they&#39;re added and removed.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>  <span class="keyword">var</span> Collection = Backbone.Collection = <span class="keyword">function</span>(models, options) {
    options || (options = {});
    <span class="keyword">if</span> (options.model) <span class="keyword">this</span>.model = options.model;
    <span class="keyword">if</span> (options.comparator !== <span class="keyword">void</span> <span class="number">0</span>) <span class="keyword">this</span>.comparator = options.comparator;
    <span class="keyword">this</span>._reset();
    <span class="keyword">this</span>.initialize.apply(<span class="keyword">this</span>, arguments);
    <span class="keyword">if</span> (models) <span class="keyword">this</span>.reset(models, _.extend({silent: <span class="literal">true</span>}, options));
  };</pre></div></div>
            
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              <p>Default options for <code>Collection#set</code>.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>  <span class="keyword">var</span> setOptions = {add: <span class="literal">true</span>, remove: <span class="literal">true</span>, merge: <span class="literal">true</span>};
  <span class="keyword">var</span> addOptions = {add: <span class="literal">true</span>, remove: <span class="literal">false</span>};</pre></div></div>
            
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              <p>Define the Collection&#39;s inheritable methods.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>  _.extend(Collection.prototype, Events, {</pre></div></div>
            
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              <p>The default model for a collection is just a <strong>Backbone.Model</strong>.
This should be overridden in most cases.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    model: Model,</pre></div></div>
            
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              <p>Initialize is an empty function by default. Override it with your own
initialization logic.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    initialize: <span class="keyword">function</span>(){},</pre></div></div>
            
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              <p>The JSON representation of a Collection is an array of the
models&#39; attributes.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    toJSON: <span class="keyword">function</span>(options) {
      <span class="keyword">return</span> <span class="keyword">this</span>.map(<span class="keyword">function</span>(model){ <span class="keyword">return</span> model.toJSON(options); });
    },</pre></div></div>
            
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              <p>Proxy <code>Backbone.sync</code> by default.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    sync: <span class="keyword">function</span>() {
      <span class="keyword">return</span> Backbone.sync.apply(<span class="keyword">this</span>, arguments);
    },</pre></div></div>
            
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              <p>Add a model, or list of models to the set.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    add: <span class="keyword">function</span>(models, options) {
      <span class="keyword">return</span> <span class="keyword">this</span>.set(models, _.extend({merge: <span class="literal">false</span>}, options, addOptions));
    },</pre></div></div>
            
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              <p>Remove a model, or a list of models from the set.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    remove: <span class="keyword">function</span>(models, options) {
      <span class="keyword">var</span> singular = !_.isArray(models);
      models = singular ? [models] : _.clone(models);
      options || (options = {});
      <span class="keyword">var</span> i, l, index, model;
      <span class="keyword">for</span> (i = <span class="number">0</span>, l = models.length; i &lt; l; i++) {
        model = models[i] = <span class="keyword">this</span>.get(models[i]);
        <span class="keyword">if</span> (!model) <span class="keyword">continue</span>;
        <span class="keyword">delete</span> <span class="keyword">this</span>._byId[model.id];
        <span class="keyword">delete</span> <span class="keyword">this</span>._byId[model.cid];
        index = <span class="keyword">this</span>.indexOf(model);
        <span class="keyword">this</span>.models.splice(index, <span class="number">1</span>);
        <span class="keyword">this</span>.length--;
        <span class="keyword">if</span> (!options.silent) {
          options.index = index;
          model.trigger(<span class="string">'remove'</span>, model, <span class="keyword">this</span>, options);
        }
        <span class="keyword">this</span>._removeReference(model);
      }
      <span class="keyword">return</span> singular ? models[<span class="number">0</span>] : models;
    },</pre></div></div>
            
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              <p>Update a collection by <code>set</code>-ing a new list of models, adding new ones,
removing models that are no longer present, and merging models that
already exist in the collection, as necessary. Similar to <strong>Model#set</strong>,
the core operation for updating the data contained by the collection.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    set: <span class="keyword">function</span>(models, options) {
      options = _.defaults({}, options, setOptions);
      <span class="keyword">if</span> (options.parse) models = <span class="keyword">this</span>.parse(models, options);
      <span class="keyword">var</span> singular = !_.isArray(models);
      models = singular ? (models ? [models] : []) : _.clone(models);
      <span class="keyword">var</span> i, l, id, model, attrs, existing, sort;
      <span class="keyword">var</span> at = options.at;
      <span class="keyword">var</span> targetModel = <span class="keyword">this</span>.model;
      <span class="keyword">var</span> sortable = <span class="keyword">this</span>.comparator &amp;&amp; (at == <span class="literal">null</span>) &amp;&amp; options.sort !== <span class="literal">false</span>;
      <span class="keyword">var</span> sortAttr = _.isString(<span class="keyword">this</span>.comparator) ? <span class="keyword">this</span>.comparator : <span class="literal">null</span>;
      <span class="keyword">var</span> toAdd = [], toRemove = [], modelMap = {};
      <span class="keyword">var</span> add = options.add, merge = options.merge, remove = options.remove;
      <span class="keyword">var</span> order = !sortable &amp;&amp; add &amp;&amp; remove ? [] : <span class="literal">false</span>;</pre></div></div>
            
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              <p>Turn bare objects into model references, and prevent invalid models
from being added.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>      <span class="keyword">for</span> (i = <span class="number">0</span>, l = models.length; i &lt; l; i++) {
        attrs = models[i];
        <span class="keyword">if</span> (attrs <span class="keyword">instanceof</span> Model) {
          id = model = attrs;
        } <span class="keyword">else</span> {
          id = attrs[targetModel.prototype.idAttribute];
        }</pre></div></div>
            
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              <p>If a duplicate is found, prevent it from being added and
optionally merge it into the existing model.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>        <span class="keyword">if</span> (existing = <span class="keyword">this</span>.get(id)) {
          <span class="keyword">if</span> (remove) modelMap[existing.cid] = <span class="literal">true</span>;
          <span class="keyword">if</span> (merge) {
            attrs = attrs === model ? model.attributes : attrs;
            <span class="keyword">if</span> (options.parse) attrs = existing.parse(attrs, options);
            existing.set(attrs, options);
            <span class="keyword">if</span> (sortable &amp;&amp; !sort &amp;&amp; existing.hasChanged(sortAttr)) sort = <span class="literal">true</span>;
          }
          models[i] = existing;</pre></div></div>
            
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              <p>If this is a new, valid model, push it to the <code>toAdd</code> list.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>        } <span class="keyword">else</span> <span class="keyword">if</span> (add) {
          model = models[i] = <span class="keyword">this</span>._prepareModel(attrs, options);
          <span class="keyword">if</span> (!model) <span class="keyword">continue</span>;
          toAdd.push(model);</pre></div></div>
            
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              </div>
              <p>Listen to added models&#39; events, and index models for lookup by
<code>id</code> and by <code>cid</code>.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>          model.on(<span class="string">'all'</span>, <span class="keyword">this</span>._onModelEvent, <span class="keyword">this</span>);
          <span class="keyword">this</span>._byId[model.cid] = model;
          <span class="keyword">if</span> (model.id != <span class="literal">null</span>) <span class="keyword">this</span>._byId[model.id] = model;
        }
        <span class="keyword">if</span> (order) order.push(existing || model);
      }</pre></div></div>
            
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              <p>Remove nonexistent models if appropriate.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>      <span class="keyword">if</span> (remove) {
        <span class="keyword">for</span> (i = <span class="number">0</span>, l = <span class="keyword">this</span>.length; i &lt; l; ++i) {
          <span class="keyword">if</span> (!modelMap[(model = <span class="keyword">this</span>.models[i]).cid]) toRemove.push(model);
        }
        <span class="keyword">if</span> (toRemove.length) <span class="keyword">this</span>.remove(toRemove, options);
      }</pre></div></div>
            
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              <p>See if sorting is needed, update <code>length</code> and splice in new models.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>      <span class="keyword">if</span> (toAdd.length || (order &amp;&amp; order.length)) {
        <span class="keyword">if</span> (sortable) sort = <span class="literal">true</span>;
        <span class="keyword">this</span>.length += toAdd.length;
        <span class="keyword">if</span> (at != <span class="literal">null</span>) {
          <span class="keyword">for</span> (i = <span class="number">0</span>, l = toAdd.length; i &lt; l; i++) {
            <span class="keyword">this</span>.models.splice(at + i, <span class="number">0</span>, toAdd[i]);
          }
        } <span class="keyword">else</span> {
          <span class="keyword">if</span> (order) <span class="keyword">this</span>.models.length = <span class="number">0</span>;
          <span class="keyword">var</span> orderedModels = order || toAdd;
          <span class="keyword">for</span> (i = <span class="number">0</span>, l = orderedModels.length; i &lt; l; i++) {
            <span class="keyword">this</span>.models.push(orderedModels[i]);
          }
        }
      }</pre></div></div>
            
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              <p>Silently sort the collection if appropriate.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>      <span class="keyword">if</span> (sort) <span class="keyword">this</span>.sort({silent: <span class="literal">true</span>});</pre></div></div>
            
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              <p>Unless silenced, it&#39;s time to fire all appropriate add/sort events.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>      <span class="keyword">if</span> (!options.silent) {
        <span class="keyword">for</span> (i = <span class="number">0</span>, l = toAdd.length; i &lt; l; i++) {
          (model = toAdd[i]).trigger(<span class="string">'add'</span>, model, <span class="keyword">this</span>, options);
        }
        <span class="keyword">if</span> (sort || (order &amp;&amp; order.length)) <span class="keyword">this</span>.trigger(<span class="string">'sort'</span>, <span class="keyword">this</span>, options);
      }</pre></div></div>
            
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              <p>Return the added (or merged) model (or models).</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>      <span class="keyword">return</span> singular ? models[<span class="number">0</span>] : models;
    },</pre></div></div>
            
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              <p>When you have more items than you want to add or remove individually,
you can reset the entire set with a new list of models, without firing
any granular <code>add</code> or <code>remove</code> events. Fires <code>reset</code> when finished.
Useful for bulk operations and optimizations.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    reset: <span class="keyword">function</span>(models, options) {
      options || (options = {});
      <span class="keyword">for</span> (<span class="keyword">var</span> i = <span class="number">0</span>, l = <span class="keyword">this</span>.models.length; i &lt; l; i++) {
        <span class="keyword">this</span>._removeReference(<span class="keyword">this</span>.models[i]);
      }
      options.previousModels = <span class="keyword">this</span>.models;
      <span class="keyword">this</span>._reset();
      models = <span class="keyword">this</span>.add(models, _.extend({silent: <span class="literal">true</span>}, options));
      <span class="keyword">if</span> (!options.silent) <span class="keyword">this</span>.trigger(<span class="string">'reset'</span>, <span class="keyword">this</span>, options);
      <span class="keyword">return</span> models;
    },</pre></div></div>
            
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              <p>Add a model to the end of the collection.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    push: <span class="keyword">function</span>(model, options) {
      <span class="keyword">return</span> <span class="keyword">this</span>.add(model, _.extend({at: <span class="keyword">this</span>.length}, options));
    },</pre></div></div>
            
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              <p>Remove a model from the end of the collection.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    pop: <span class="keyword">function</span>(options) {
      <span class="keyword">var</span> model = <span class="keyword">this</span>.at(<span class="keyword">this</span>.length - <span class="number">1</span>);
      <span class="keyword">this</span>.remove(model, options);
      <span class="keyword">return</span> model;
    },</pre></div></div>
            
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              <p>Add a model to the beginning of the collection.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    unshift: <span class="keyword">function</span>(model, options) {
      <span class="keyword">return</span> <span class="keyword">this</span>.add(model, _.extend({at: <span class="number">0</span>}, options));
    },</pre></div></div>
            
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              <p>Remove a model from the beginning of the collection.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    shift: <span class="keyword">function</span>(options) {
      <span class="keyword">var</span> model = <span class="keyword">this</span>.at(<span class="number">0</span>);
      <span class="keyword">this</span>.remove(model, options);
      <span class="keyword">return</span> model;
    },</pre></div></div>
            
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              <p>Slice out a sub-array of models from the collection.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    slice: <span class="keyword">function</span>() {
      <span class="keyword">return</span> slice.apply(<span class="keyword">this</span>.models, arguments);
    },</pre></div></div>
            
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              <p>Get a model from the set by id.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    get: <span class="keyword">function</span>(obj) {
      <span class="keyword">if</span> (obj == <span class="literal">null</span>) <span class="keyword">return</span> <span class="keyword">void</span> <span class="number">0</span>;
      <span class="keyword">return</span> <span class="keyword">this</span>._byId[obj.id] || <span class="keyword">this</span>._byId[obj.cid] || <span class="keyword">this</span>._byId[obj];
    },</pre></div></div>
            
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              <p>Get the model at the given index.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    at: <span class="keyword">function</span>(index) {
      <span class="keyword">return</span> <span class="keyword">this</span>.models[index];
    },</pre></div></div>
            
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              <p>Return models with matching attributes. Useful for simple cases of
<code>filter</code>.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    where: <span class="keyword">function</span>(attrs, first) {
      <span class="keyword">if</span> (_.isEmpty(attrs)) <span class="keyword">return</span> first ? <span class="keyword">void</span> <span class="number">0</span> : [];
      <span class="keyword">return</span> <span class="keyword">this</span>[first ? <span class="string">'find'</span> : <span class="string">'filter'</span>](<span class="keyword">function</span>(model) {
        <span class="keyword">for</span> (<span class="keyword">var</span> key <span class="keyword">in</span> attrs) {
          <span class="keyword">if</span> (attrs[key] !== model.get(key)) <span class="keyword">return</span> <span class="literal">false</span>;
        }
        <span class="keyword">return</span> <span class="literal">true</span>;
      });
    },</pre></div></div>
            
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              <p>Return the first model with matching attributes. Useful for simple cases
of <code>find</code>.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    findWhere: <span class="keyword">function</span>(attrs) {
      <span class="keyword">return</span> <span class="keyword">this</span>.where(attrs, <span class="literal">true</span>);
    },</pre></div></div>
            
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              <p>Force the collection to re-sort itself. You don&#39;t need to call this under
normal circumstances, as the set will maintain sort order as each item
is added.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    sort: <span class="keyword">function</span>(options) {
      <span class="keyword">if</span> (!<span class="keyword">this</span>.comparator) <span class="keyword">throw</span> <span class="keyword">new</span> Error(<span class="string">'Cannot sort a set without a comparator'</span>);
      options || (options = {});</pre></div></div>
            
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              <p>Run sort based on type of <code>comparator</code>.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>      <span class="keyword">if</span> (_.isString(<span class="keyword">this</span>.comparator) || <span class="keyword">this</span>.comparator.length === <span class="number">1</span>) {
        <span class="keyword">this</span>.models = <span class="keyword">this</span>.sortBy(<span class="keyword">this</span>.comparator, <span class="keyword">this</span>);
      } <span class="keyword">else</span> {
        <span class="keyword">this</span>.models.sort(_.bind(<span class="keyword">this</span>.comparator, <span class="keyword">this</span>));
      }

      <span class="keyword">if</span> (!options.silent) <span class="keyword">this</span>.trigger(<span class="string">'sort'</span>, <span class="keyword">this</span>, options);
      <span class="keyword">return</span> <span class="keyword">this</span>;
    },</pre></div></div>
            
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              <p>Pluck an attribute from each model in the collection.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    pluck: <span class="keyword">function</span>(attr) {
      <span class="keyword">return</span> _.invoke(<span class="keyword">this</span>.models, <span class="string">'get'</span>, attr);
    },</pre></div></div>
            
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              <p>Fetch the default set of models for this collection, resetting the
collection when they arrive. If <code>reset: true</code> is passed, the response
data will be passed through the <code>reset</code> method instead of <code>set</code>.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    fetch: <span class="keyword">function</span>(options) {
      options = options ? _.clone(options) : {};
      <span class="keyword">if</span> (options.parse === <span class="keyword">void</span> <span class="number">0</span>) options.parse = <span class="literal">true</span>;
      <span class="keyword">var</span> success = options.success;
      <span class="keyword">var</span> collection = <span class="keyword">this</span>;
      options.success = <span class="keyword">function</span>(resp) {
        <span class="keyword">var</span> method = options.reset ? <span class="string">'reset'</span> : <span class="string">'set'</span>;
        collection[method](resp, options);
        <span class="keyword">if</span> (success) success(collection, resp, options);
        collection.trigger(<span class="string">'sync'</span>, collection, resp, options);
      };
      wrapError(<span class="keyword">this</span>, options);
      <span class="keyword">return</span> <span class="keyword">this</span>.sync(<span class="string">'read'</span>, <span class="keyword">this</span>, options);
    },</pre></div></div>
            
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              <p>Create a new instance of a model in this collection. Add the model to the
collection immediately, unless <code>wait: true</code> is passed, in which case we
wait for the server to agree.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    create: <span class="keyword">function</span>(model, options) {
      options = options ? _.clone(options) : {};
      <span class="keyword">if</span> (!(model = <span class="keyword">this</span>._prepareModel(model, options))) <span class="keyword">return</span> <span class="literal">false</span>;
      <span class="keyword">if</span> (!options.wait) <span class="keyword">this</span>.add(model, options);
      <span class="keyword">var</span> collection = <span class="keyword">this</span>;
      <span class="keyword">var</span> success = options.success;
      options.success = <span class="keyword">function</span>(model, resp, options) {
        <span class="keyword">if</span> (options.wait) collection.add(model, options);
        <span class="keyword">if</span> (success) success(model, resp, options);
      };
      model.save(<span class="literal">null</span>, options);
      <span class="keyword">return</span> model;
    },</pre></div></div>
            
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              <p><strong>parse</strong> converts a response into a list of models to be added to the
collection. The default implementation is just to pass it through.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    parse: <span class="keyword">function</span>(resp, options) {
      <span class="keyword">return</span> resp;
    },</pre></div></div>
            
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              <p>Create a new collection with an identical list of models as this one.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    clone: <span class="keyword">function</span>() {
      <span class="keyword">return</span> <span class="keyword">new</span> <span class="keyword">this</span>.constructor(<span class="keyword">this</span>.models);
    },</pre></div></div>
            
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              <p>Private method to reset all internal state. Called when the collection
is first initialized or reset.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    _reset: <span class="keyword">function</span>() {
      <span class="keyword">this</span>.length = <span class="number">0</span>;
      <span class="keyword">this</span>.models = [];
      <span class="keyword">this</span>._byId  = {};
    },</pre></div></div>
            
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              <p>Prepare a hash of attributes (or other model) to be added to this
collection.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    _prepareModel: <span class="keyword">function</span>(attrs, options) {
      <span class="keyword">if</span> (attrs <span class="keyword">instanceof</span> Model) {
        <span class="keyword">if</span> (!attrs.collection) attrs.collection = <span class="keyword">this</span>;
        <span class="keyword">return</span> attrs;
      }
      options = options ? _.clone(options) : {};
      options.collection = <span class="keyword">this</span>;
      <span class="keyword">var</span> model = <span class="keyword">new</span> <span class="keyword">this</span>.model(attrs, options);
      <span class="keyword">if</span> (!model.validationError) <span class="keyword">return</span> model;
      <span class="keyword">this</span>.trigger(<span class="string">'invalid'</span>, <span class="keyword">this</span>, model.validationError, options);
      <span class="keyword">return</span> <span class="literal">false</span>;
    },</pre></div></div>
            
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              <p>Internal method to sever a model&#39;s ties to a collection.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    _removeReference: <span class="keyword">function</span>(model) {
      <span class="keyword">if</span> (<span class="keyword">this</span> === model.collection) <span class="keyword">delete</span> model.collection;
      model.off(<span class="string">'all'</span>, <span class="keyword">this</span>._onModelEvent, <span class="keyword">this</span>);
    },</pre></div></div>
            
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              <p>Internal method called every time a model in the set fires an event.
Sets need to update their indexes when models change ids. All other
events simply proxy through. &quot;add&quot; and &quot;remove&quot; events that originate
in other collections are ignored.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    _onModelEvent: <span class="keyword">function</span>(event, model, collection, options) {
      <span class="keyword">if</span> ((event === <span class="string">'add'</span> || event === <span class="string">'remove'</span>) &amp;&amp; collection !== <span class="keyword">this</span>) <span class="keyword">return</span>;
      <span class="keyword">if</span> (event === <span class="string">'destroy'</span>) <span class="keyword">this</span>.remove(model, options);
      <span class="keyword">if</span> (model &amp;&amp; event === <span class="string">'change:'</span> + model.idAttribute) {
        <span class="keyword">delete</span> <span class="keyword">this</span>._byId[model.previous(model.idAttribute)];
        <span class="keyword">if</span> (model.id != <span class="literal">null</span>) <span class="keyword">this</span>._byId[model.id] = model;
      }
      <span class="keyword">this</span>.trigger.apply(<span class="keyword">this</span>, arguments);
    }

  });</pre></div></div>
            
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              <p>Underscore methods that we want to implement on the Collection.
90% of the core usefulness of Backbone Collections is actually implemented
right here:</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>  <span class="keyword">var</span> methods = [<span class="string">'forEach'</span>, <span class="string">'each'</span>, <span class="string">'map'</span>, <span class="string">'collect'</span>, <span class="string">'reduce'</span>, <span class="string">'foldl'</span>,
    <span class="string">'inject'</span>, <span class="string">'reduceRight'</span>, <span class="string">'foldr'</span>, <span class="string">'find'</span>, <span class="string">'detect'</span>, <span class="string">'filter'</span>, <span class="string">'select'</span>,
    <span class="string">'reject'</span>, <span class="string">'every'</span>, <span class="string">'all'</span>, <span class="string">'some'</span>, <span class="string">'any'</span>, <span class="string">'include'</span>, <span class="string">'contains'</span>, <span class="string">'invoke'</span>,
    <span class="string">'max'</span>, <span class="string">'min'</span>, <span class="string">'toArray'</span>, <span class="string">'size'</span>, <span class="string">'first'</span>, <span class="string">'head'</span>, <span class="string">'take'</span>, <span class="string">'initial'</span>, <span class="string">'rest'</span>,
    <span class="string">'tail'</span>, <span class="string">'drop'</span>, <span class="string">'last'</span>, <span class="string">'without'</span>, <span class="string">'difference'</span>, <span class="string">'indexOf'</span>, <span class="string">'shuffle'</span>,
    <span class="string">'lastIndexOf'</span>, <span class="string">'isEmpty'</span>, <span class="string">'chain'</span>];</pre></div></div>
            
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              <p>Mix in each Underscore method as a proxy to <code>Collection#models</code>.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>  _.each(methods, <span class="keyword">function</span>(method) {
    Collection.prototype[method] = <span class="keyword">function</span>() {
      <span class="keyword">var</span> args = slice.call(arguments);
      args.unshift(<span class="keyword">this</span>.models);
      <span class="keyword">return</span> _[method].apply(_, args);
    };
  });</pre></div></div>
            
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              <p>Underscore methods that take a property name as an argument.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>  <span class="keyword">var</span> attributeMethods = [<span class="string">'groupBy'</span>, <span class="string">'countBy'</span>, <span class="string">'sortBy'</span>];</pre></div></div>
            
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              <p>Use attributes instead of properties.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>  _.each(attributeMethods, <span class="keyword">function</span>(method) {
    Collection.prototype[method] = <span class="keyword">function</span>(value, context) {
      <span class="keyword">var</span> iterator = _.isFunction(value) ? value : <span class="keyword">function</span>(model) {
        <span class="keyword">return</span> model.get(value);
      };
      <span class="keyword">return</span> _[method](<span class="keyword">this</span>.models, iterator, context);
    };
  });</pre></div></div>
            
        </li>
        
        
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              <h2>Backbone.View</h2>

            </div>
            
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              <p>Backbone Views are almost more convention than they are actual code. A View
is simply a JavaScript object that represents a logical chunk of UI in the
DOM. This might be a single item, an entire list, a sidebar or panel, or
even the surrounding frame which wraps your whole app. Defining a chunk of
UI as a <strong>View</strong> allows you to define your DOM events declaratively, without
having to worry about render order ... and makes it easy for the view to
react to specific changes in the state of your models.</p>
<p>Creating a Backbone.View creates its initial element outside of the DOM,
if an existing element is not provided...</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>  <span class="keyword">var</span> View = Backbone.View = <span class="keyword">function</span>(options) {
    <span class="keyword">this</span>.cid = _.uniqueId(<span class="string">'view'</span>);
    options || (options = {});
    _.extend(<span class="keyword">this</span>, _.pick(options, viewOptions));
    <span class="keyword">this</span>._ensureElement();
    <span class="keyword">this</span>.initialize.apply(<span class="keyword">this</span>, arguments);
    <span class="keyword">this</span>.delegateEvents();
  };</pre></div></div>
            
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              <p>Cached regex to split keys for <code>delegate</code>.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>  <span class="keyword">var</span> delegateEventSplitter = <span class="regexp">/^(\S+)\s*(.*)$/</span>;</pre></div></div>
            
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              <p>List of view options to be merged as properties.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>  <span class="keyword">var</span> viewOptions = [<span class="string">'model'</span>, <span class="string">'collection'</span>, <span class="string">'el'</span>, <span class="string">'id'</span>, <span class="string">'attributes'</span>, <span class="string">'className'</span>, <span class="string">'tagName'</span>, <span class="string">'events'</span>];</pre></div></div>
            
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              <p>Set up all inheritable <strong>Backbone.View</strong> properties and methods.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>  _.extend(View.prototype, Events, {</pre></div></div>
            
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              <p>The default <code>tagName</code> of a View&#39;s element is <code>&quot;div&quot;</code>.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    tagName: <span class="string">'div'</span>,</pre></div></div>
            
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              <p>jQuery delegate for element lookup, scoped to DOM elements within the
current view. This should be preferred to global lookups where possible.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    $: <span class="keyword">function</span>(selector) {
      <span class="keyword">return</span> <span class="keyword">this</span>.$el.find(selector);
    },</pre></div></div>
            
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              <p>Initialize is an empty function by default. Override it with your own
initialization logic.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    initialize: <span class="keyword">function</span>(){},</pre></div></div>
            
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              <p><strong>render</strong> is the core function that your view should override, in order
to populate its element (<code>this.el</code>), with the appropriate HTML. The
convention is for <strong>render</strong> to always return <code>this</code>.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    render: <span class="keyword">function</span>() {
      <span class="keyword">return</span> <span class="keyword">this</span>;
    },</pre></div></div>
            
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              <p>Remove this view by taking the element out of the DOM, and removing any
applicable Backbone.Events listeners.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    remove: <span class="keyword">function</span>() {
      <span class="keyword">this</span>.$el.remove();
      <span class="keyword">this</span>.stopListening();
      <span class="keyword">return</span> <span class="keyword">this</span>;
    },</pre></div></div>
            
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              <p>Change the view&#39;s element (<code>this.el</code> property), including event
re-delegation.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    setElement: <span class="keyword">function</span>(element, delegate) {
      <span class="keyword">if</span> (<span class="keyword">this</span>.$el) <span class="keyword">this</span>.undelegateEvents();
      <span class="keyword">this</span>.$el = element <span class="keyword">instanceof</span> Backbone.$ ? element : Backbone.$(element);
      <span class="keyword">this</span>.el = <span class="keyword">this</span>.$el[<span class="number">0</span>];
      <span class="keyword">if</span> (delegate !== <span class="literal">false</span>) <span class="keyword">this</span>.delegateEvents();
      <span class="keyword">return</span> <span class="keyword">this</span>;
    },</pre></div></div>
            
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              <p>Set callbacks, where <code>this.events</code> is a hash of</p>
<p><em>{&quot;event selector&quot;: &quot;callback&quot;}</em></p>
<pre><code>{
  &#39;mousedown .title&#39;:  &#39;edit&#39;,
  &#39;click .button&#39;:     &#39;save&#39;,
  &#39;click .open&#39;:       function(e) { ... }
}</code></pre>
<p>pairs. Callbacks will be bound to the view, with <code>this</code> set properly.
Uses event delegation for efficiency.
Omitting the selector binds the event to <code>this.el</code>.
This only works for delegate-able events: not <code>focus</code>, <code>blur</code>, and
not <code>change</code>, <code>submit</code>, and <code>reset</code> in Internet Explorer.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    delegateEvents: <span class="keyword">function</span>(events) {
      <span class="keyword">if</span> (!(events || (events = _.result(<span class="keyword">this</span>, <span class="string">'events'</span>)))) <span class="keyword">return</span> <span class="keyword">this</span>;
      <span class="keyword">this</span>.undelegateEvents();
      <span class="keyword">for</span> (<span class="keyword">var</span> key <span class="keyword">in</span> events) {
        <span class="keyword">var</span> method = events[key];
        <span class="keyword">if</span> (!_.isFunction(method)) method = <span class="keyword">this</span>[events[key]];
        <span class="keyword">if</span> (!method) <span class="keyword">continue</span>;

        <span class="keyword">var</span> match = key.match(delegateEventSplitter);
        <span class="keyword">var</span> eventName = match[<span class="number">1</span>], selector = match[<span class="number">2</span>];
        method = _.bind(method, <span class="keyword">this</span>);
        eventName += <span class="string">'.delegateEvents'</span> + <span class="keyword">this</span>.cid;
        <span class="keyword">if</span> (selector === <span class="string">''</span>) {
          <span class="keyword">this</span>.$el.on(eventName, method);
        } <span class="keyword">else</span> {
          <span class="keyword">this</span>.$el.on(eventName, selector, method);
        }
      }
      <span class="keyword">return</span> <span class="keyword">this</span>;
    },</pre></div></div>
            
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              <p>Clears all callbacks previously bound to the view with <code>delegateEvents</code>.
You usually don&#39;t need to use this, but may wish to if you have multiple
Backbone views attached to the same DOM element.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    undelegateEvents: <span class="keyword">function</span>() {
      <span class="keyword">this</span>.$el.off(<span class="string">'.delegateEvents'</span> + <span class="keyword">this</span>.cid);
      <span class="keyword">return</span> <span class="keyword">this</span>;
    },</pre></div></div>
            
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              <p>Ensure that the View has a DOM element to render into.
If <code>this.el</code> is a string, pass it through <code>$()</code>, take the first
matching element, and re-assign it to <code>el</code>. Otherwise, create
an element from the <code>id</code>, <code>className</code> and <code>tagName</code> properties.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    _ensureElement: <span class="keyword">function</span>() {
      <span class="keyword">if</span> (!<span class="keyword">this</span>.el) {
        <span class="keyword">var</span> attrs = _.extend({}, _.result(<span class="keyword">this</span>, <span class="string">'attributes'</span>));
        <span class="keyword">if</span> (<span class="keyword">this</span>.id) attrs.id = _.result(<span class="keyword">this</span>, <span class="string">'id'</span>);
        <span class="keyword">if</span> (<span class="keyword">this</span>.className) attrs[<span class="string">'class'</span>] = _.result(<span class="keyword">this</span>, <span class="string">'className'</span>);
        <span class="keyword">var</span> $el = Backbone.$(<span class="string">'&lt;'</span> + _.result(<span class="keyword">this</span>, <span class="string">'tagName'</span>) + <span class="string">'&gt;'</span>).attr(attrs);
        <span class="keyword">this</span>.setElement($el, <span class="literal">false</span>);
      } <span class="keyword">else</span> {
        <span class="keyword">this</span>.setElement(_.result(<span class="keyword">this</span>, <span class="string">'el'</span>), <span class="literal">false</span>);
      }
    }

  });</pre></div></div>
            
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            <div class="annotation">
              
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              <h2>Backbone.sync</h2>

            </div>
            
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              <p>Override this function to change the manner in which Backbone persists
models to the server. You will be passed the type of request, and the
model in question. By default, makes a RESTful Ajax request
to the model&#39;s <code>url()</code>. Some possible customizations could be:</p>
<ul>
<li>Use <code>setTimeout</code> to batch rapid-fire updates into a single request.</li>
<li>Send up the models as XML instead of JSON.</li>
<li>Persist models via WebSockets instead of Ajax.</li>
</ul>
<p>Turn on <code>Backbone.emulateHTTP</code> in order to send <code>PUT</code> and <code>DELETE</code> requests
as <code>POST</code>, with a <code>_method</code> parameter containing the true HTTP method,
as well as all requests with the body as <code>application/x-www-form-urlencoded</code>
instead of <code>application/json</code> with the model in a param named <code>model</code>.
Useful when interfacing with server-side languages like <strong>PHP</strong> that make
it difficult to read the body of <code>PUT</code> requests.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>  Backbone.sync = <span class="keyword">function</span>(method, model, options) {
    <span class="keyword">var</span> type = methodMap[method];</pre></div></div>
            
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              <p>Default options, unless specified.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    _.defaults(options || (options = {}), {
      emulateHTTP: Backbone.emulateHTTP,
      emulateJSON: Backbone.emulateJSON
    });</pre></div></div>
            
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              <p>Default JSON-request options.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    <span class="keyword">var</span> params = {type: type, dataType: <span class="string">'json'</span>};</pre></div></div>
            
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              <p>Ensure that we have a URL.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    <span class="keyword">if</span> (!options.url) {
      params.url = _.result(model, <span class="string">'url'</span>) || urlError();
    }</pre></div></div>
            
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              <p>Ensure that we have the appropriate request data.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    <span class="keyword">if</span> (options.data == <span class="literal">null</span> &amp;&amp; model &amp;&amp; (method === <span class="string">'create'</span> || method === <span class="string">'update'</span> || method === <span class="string">'patch'</span>)) {
      params.contentType = <span class="string">'application/json'</span>;
      params.data = JSON.stringify(options.attrs || model.toJSON(options));
    }</pre></div></div>
            
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              <p>For older servers, emulate JSON by encoding the request into an HTML-form.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    <span class="keyword">if</span> (options.emulateJSON) {
      params.contentType = <span class="string">'application/x-www-form-urlencoded'</span>;
      params.data = params.data ? {model: params.data} : {};
    }</pre></div></div>
            
        </li>
        
        
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              <p>For older servers, emulate HTTP by mimicking the HTTP method with <code>_method</code>
And an <code>X-HTTP-Method-Override</code> header.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    <span class="keyword">if</span> (options.emulateHTTP &amp;&amp; (type === <span class="string">'PUT'</span> || type === <span class="string">'DELETE'</span> || type === <span class="string">'PATCH'</span>)) {
      params.type = <span class="string">'POST'</span>;
      <span class="keyword">if</span> (options.emulateJSON) params.data._method = type;
      <span class="keyword">var</span> beforeSend = options.beforeSend;
      options.beforeSend = <span class="keyword">function</span>(xhr) {
        xhr.setRequestHeader(<span class="string">'X-HTTP-Method-Override'</span>, type);
        <span class="keyword">if</span> (beforeSend) <span class="keyword">return</span> beforeSend.apply(<span class="keyword">this</span>, arguments);
      };
    }</pre></div></div>
            
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              <p>Don&#39;t process data on a non-GET request.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    <span class="keyword">if</span> (params.type !== <span class="string">'GET'</span> &amp;&amp; !options.emulateJSON) {
      params.processData = <span class="literal">false</span>;
    }</pre></div></div>
            
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              <p>If we&#39;re sending a <code>PATCH</code> request, and we&#39;re in an old Internet Explorer
that still has ActiveX enabled by default, override jQuery to use that
for XHR instead. Remove this line when jQuery supports <code>PATCH</code> on IE8.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    <span class="keyword">if</span> (params.type === <span class="string">'PATCH'</span> &amp;&amp; noXhrPatch) {
      params.xhr = <span class="keyword">function</span>() {
        <span class="keyword">return</span> <span class="keyword">new</span> ActiveXObject(<span class="string">"Microsoft.XMLHTTP"</span>);
      };
    }</pre></div></div>
            
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              <p>Make the request, allowing the user to override any Ajax options.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    <span class="keyword">var</span> xhr = options.xhr = Backbone.ajax(_.extend(params, options));
    model.trigger(<span class="string">'request'</span>, model, xhr, options);
    <span class="keyword">return</span> xhr;
  };

  <span class="keyword">var</span> noXhrPatch = <span class="keyword">typeof</span> window !== <span class="string">'undefined'</span> &amp;&amp; !!window.ActiveXObject &amp;&amp; !(window.XMLHttpRequest &amp;&amp; (<span class="keyword">new</span> XMLHttpRequest).dispatchEvent);</pre></div></div>
            
        </li>
        
        
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              <p>Map from CRUD to HTTP for our default <code>Backbone.sync</code> implementation.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>  <span class="keyword">var</span> methodMap = {
    <span class="string">'create'</span>: <span class="string">'POST'</span>,
    <span class="string">'update'</span>: <span class="string">'PUT'</span>,
    <span class="string">'patch'</span>:  <span class="string">'PATCH'</span>,
    <span class="string">'delete'</span>: <span class="string">'DELETE'</span>,
    <span class="string">'read'</span>:   <span class="string">'GET'</span>
  };</pre></div></div>
            
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              <p>Set the default implementation of <code>Backbone.ajax</code> to proxy through to <code>$</code>.
Override this if you&#39;d like to use a different library.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>  Backbone.ajax = <span class="keyword">function</span>() {
    <span class="keyword">return</span> Backbone.$.ajax.apply(Backbone.$, arguments);
  };</pre></div></div>
            
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        <li id="section-143">
            <div class="annotation">
              
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              </div>
              <h2>Backbone.Router</h2>

            </div>
            
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              <p>Routers map faux-URLs to actions, and fire events when routes are
matched. Creating a new one sets its <code>routes</code> hash, if not set statically.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>  <span class="keyword">var</span> Router = Backbone.Router = <span class="keyword">function</span>(options) {
    options || (options = {});
    <span class="keyword">if</span> (options.routes) <span class="keyword">this</span>.routes = options.routes;
    <span class="keyword">this</span>._bindRoutes();
    <span class="keyword">this</span>.initialize.apply(<span class="keyword">this</span>, arguments);
  };</pre></div></div>
            
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              <p>Cached regular expressions for matching named param parts and splatted
parts of route strings.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>  <span class="keyword">var</span> optionalParam = <span class="regexp">/\((.*?)\)/g</span>;
  <span class="keyword">var</span> namedParam    = <span class="regexp">/(\(\?)?:\w+/g</span>;
  <span class="keyword">var</span> splatParam    = <span class="regexp">/\*\w+/g</span>;
  <span class="keyword">var</span> escapeRegExp  = <span class="regexp">/[\-{}\[\]+?.,\\\^$|#\s]/g</span>;</pre></div></div>
            
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              <p>Set up all inheritable <strong>Backbone.Router</strong> properties and methods.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>  _.extend(Router.prototype, Events, {</pre></div></div>
            
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              <p>Initialize is an empty function by default. Override it with your own
initialization logic.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    initialize: <span class="keyword">function</span>(){},</pre></div></div>
            
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              <p>Manually bind a single named route to a callback. For example:</p>
<pre><code>this.route(&#39;search/:query/p:num&#39;, &#39;search&#39;, function(query, num) {
  ...
});</code></pre>

            </div>
            
            <div class="content"><div class='highlight'><pre>    route: <span class="keyword">function</span>(route, name, callback) {
      <span class="keyword">if</span> (!_.isRegExp(route)) route = <span class="keyword">this</span>._routeToRegExp(route);
      <span class="keyword">if</span> (_.isFunction(name)) {
        callback = name;
        name = <span class="string">''</span>;
      }
      <span class="keyword">if</span> (!callback) callback = <span class="keyword">this</span>[name];
      <span class="keyword">var</span> router = <span class="keyword">this</span>;
      Backbone.history.route(route, <span class="keyword">function</span>(fragment) {
        <span class="keyword">var</span> args = router._extractParameters(route, fragment);
        callback &amp;&amp; callback.apply(router, args);
        router.trigger.apply(router, [<span class="string">'route:'</span> + name].concat(args));
        router.trigger(<span class="string">'route'</span>, name, args);
        Backbone.history.trigger(<span class="string">'route'</span>, router, name, args);
      });
      <span class="keyword">return</span> <span class="keyword">this</span>;
    },</pre></div></div>
            
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              <p>Simple proxy to <code>Backbone.history</code> to save a fragment into the history.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    navigate: <span class="keyword">function</span>(fragment, options) {
      Backbone.history.navigate(fragment, options);
      <span class="keyword">return</span> <span class="keyword">this</span>;
    },</pre></div></div>
            
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              <p>Bind all defined routes to <code>Backbone.history</code>. We have to reverse the
order of the routes here to support behavior where the most general
routes can be defined at the bottom of the route map.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    _bindRoutes: <span class="keyword">function</span>() {
      <span class="keyword">if</span> (!<span class="keyword">this</span>.routes) <span class="keyword">return</span>;
      <span class="keyword">this</span>.routes = _.result(<span class="keyword">this</span>, <span class="string">'routes'</span>);
      <span class="keyword">var</span> route, routes = _.keys(<span class="keyword">this</span>.routes);
      <span class="keyword">while</span> ((route = routes.pop()) != <span class="literal">null</span>) {
        <span class="keyword">this</span>.route(route, <span class="keyword">this</span>.routes[route]);
      }
    },</pre></div></div>
            
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              <p>Convert a route string into a regular expression, suitable for matching
against the current location hash.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    _routeToRegExp: <span class="keyword">function</span>(route) {
      route = route.replace(escapeRegExp, <span class="string">'\\$&amp;'</span>)
                   .replace(optionalParam, <span class="string">'(?:$1)?'</span>)
                   .replace(namedParam, <span class="keyword">function</span>(match, optional) {
                     <span class="keyword">return</span> optional ? match : <span class="string">'([^\/]+)'</span>;
                   })
                   .replace(splatParam, <span class="string">'(.*?)'</span>);
      <span class="keyword">return</span> <span class="keyword">new</span> RegExp(<span class="string">'^'</span> + route + <span class="string">'$'</span>);
    },</pre></div></div>
            
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              <p>Given a route, and a URL fragment that it matches, return the array of
extracted decoded parameters. Empty or unmatched parameters will be
treated as <code>null</code> to normalize cross-browser behavior.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    _extractParameters: <span class="keyword">function</span>(route, fragment) {
      <span class="keyword">var</span> params = route.exec(fragment).slice(<span class="number">1</span>);
      <span class="keyword">return</span> _.map(params, <span class="keyword">function</span>(param) {
        <span class="keyword">return</span> param ? decodeURIComponent(param) : <span class="literal">null</span>;
      });
    }

  });</pre></div></div>
            
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              <h2>Backbone.History</h2>

            </div>
            
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              <p>Handles cross-browser history management, based on either
<a href="http://diveintohtml5.info/history.html">pushState</a> and real URLs, or
<a href="https://developer.mozilla.org/en-US/docs/DOM/window.onhashchange">onhashchange</a>
and URL fragments. If the browser supports neither (old IE, natch),
falls back to polling.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>  <span class="keyword">var</span> History = Backbone.History = <span class="keyword">function</span>() {
    <span class="keyword">this</span>.handlers = [];
    _.bindAll(<span class="keyword">this</span>, <span class="string">'checkUrl'</span>);</pre></div></div>
            
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              <p>Ensure that <code>History</code> can be used outside of the browser.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    <span class="keyword">if</span> (<span class="keyword">typeof</span> window !== <span class="string">'undefined'</span>) {
      <span class="keyword">this</span>.location = window.location;
      <span class="keyword">this</span>.history = window.history;
    }
  };</pre></div></div>
            
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              <p>Cached regex for stripping a leading hash/slash and trailing space.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>  <span class="keyword">var</span> routeStripper = <span class="regexp">/^[#\/]|\s+$/g</span>;</pre></div></div>
            
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              <p>Cached regex for stripping leading and trailing slashes.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>  <span class="keyword">var</span> rootStripper = <span class="regexp">/^\/+|\/+$/g</span>;</pre></div></div>
            
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              <p>Cached regex for detecting MSIE.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>  <span class="keyword">var</span> isExplorer = <span class="regexp">/msie [\w.]+/</span>;</pre></div></div>
            
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              <p>Cached regex for removing a trailing slash.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>  <span class="keyword">var</span> trailingSlash = <span class="regexp">/\/$/</span>;</pre></div></div>
            
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              <p>Cached regex for stripping urls of hash and query.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>  <span class="keyword">var</span> pathStripper = <span class="regexp">/[?#].*$/</span>;</pre></div></div>
            
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              <p>Has the history handling already been started?</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>  History.started = <span class="literal">false</span>;</pre></div></div>
            
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              <p>Set up all inheritable <strong>Backbone.History</strong> properties and methods.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>  _.extend(History.prototype, Events, {</pre></div></div>
            
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              <p>The default interval to poll for hash changes, if necessary, is
twenty times a second.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    interval: <span class="number">50</span>,</pre></div></div>
            
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              <p>Gets the true hash value. Cannot use location.hash directly due to bug
in Firefox where location.hash will always be decoded.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    getHash: <span class="keyword">function</span>(window) {
      <span class="keyword">var</span> match = (window || <span class="keyword">this</span>).location.href.match(<span class="regexp">/#(.*)$/</span>);
      <span class="keyword">return</span> match ? match[<span class="number">1</span>] : <span class="string">''</span>;
    },</pre></div></div>
            
        </li>
        
        
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              <p>Get the cross-browser normalized URL fragment, either from the URL,
the hash, or the override.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    getFragment: <span class="keyword">function</span>(fragment, forcePushState) {
      <span class="keyword">if</span> (fragment == <span class="literal">null</span>) {
        <span class="keyword">if</span> (<span class="keyword">this</span>._hasPushState || !<span class="keyword">this</span>._wantsHashChange || forcePushState) {
          fragment = <span class="keyword">this</span>.location.pathname;
          <span class="keyword">var</span> root = <span class="keyword">this</span>.root.replace(trailingSlash, <span class="string">''</span>);
          <span class="keyword">if</span> (!fragment.indexOf(root)) fragment = fragment.slice(root.length);
        } <span class="keyword">else</span> {
          fragment = <span class="keyword">this</span>.getHash();
        }
      }
      <span class="keyword">return</span> fragment.replace(routeStripper, <span class="string">''</span>);
    },</pre></div></div>
            
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              <p>Start the hash change handling, returning <code>true</code> if the current URL matches
an existing route, and <code>false</code> otherwise.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    start: <span class="keyword">function</span>(options) {
      <span class="keyword">if</span> (History.started) <span class="keyword">throw</span> <span class="keyword">new</span> Error(<span class="string">"Backbone.history has already been started"</span>);
      History.started = <span class="literal">true</span>;</pre></div></div>
            
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              <p>Figure out the initial configuration. Do we need an iframe?
Is pushState desired ... is it available?</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>      <span class="keyword">this</span>.options          = _.extend({root: <span class="string">'/'</span>}, <span class="keyword">this</span>.options, options);
      <span class="keyword">this</span>.root             = <span class="keyword">this</span>.options.root;
      <span class="keyword">this</span>._wantsHashChange = <span class="keyword">this</span>.options.hashChange !== <span class="literal">false</span>;
      <span class="keyword">this</span>._wantsPushState  = !!<span class="keyword">this</span>.options.pushState;
      <span class="keyword">this</span>._hasPushState    = !!(<span class="keyword">this</span>.options.pushState &amp;&amp; <span class="keyword">this</span>.history &amp;&amp; <span class="keyword">this</span>.history.pushState);
      <span class="keyword">var</span> fragment          = <span class="keyword">this</span>.getFragment();
      <span class="keyword">var</span> docMode           = document.documentMode;
      <span class="keyword">var</span> oldIE             = (isExplorer.exec(navigator.userAgent.toLowerCase()) &amp;&amp; (!docMode || docMode &lt;= <span class="number">7</span>));</pre></div></div>
            
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              <p>Normalize root to always include a leading and trailing slash.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>      <span class="keyword">this</span>.root = (<span class="string">'/'</span> + <span class="keyword">this</span>.root + <span class="string">'/'</span>).replace(rootStripper, <span class="string">'/'</span>);

      <span class="keyword">if</span> (oldIE &amp;&amp; <span class="keyword">this</span>._wantsHashChange) {
        <span class="keyword">this</span>.iframe = Backbone.$(<span class="string">'&lt;iframe src="javascript:0" tabindex="-1" /&gt;'</span>).hide().appendTo(<span class="string">'body'</span>)[<span class="number">0</span>].contentWindow;
        <span class="keyword">this</span>.navigate(fragment);
      }</pre></div></div>
            
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              <p>Depending on whether we&#39;re using pushState or hashes, and whether
&#39;onhashchange&#39; is supported, determine how we check the URL state.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>      <span class="keyword">if</span> (<span class="keyword">this</span>._hasPushState) {
        Backbone.$(window).on(<span class="string">'popstate'</span>, <span class="keyword">this</span>.checkUrl);
      } <span class="keyword">else</span> <span class="keyword">if</span> (<span class="keyword">this</span>._wantsHashChange &amp;&amp; (<span class="string">'onhashchange'</span> <span class="keyword">in</span> window) &amp;&amp; !oldIE) {
        Backbone.$(window).on(<span class="string">'hashchange'</span>, <span class="keyword">this</span>.checkUrl);
      } <span class="keyword">else</span> <span class="keyword">if</span> (<span class="keyword">this</span>._wantsHashChange) {
        <span class="keyword">this</span>._checkUrlInterval = setInterval(<span class="keyword">this</span>.checkUrl, <span class="keyword">this</span>.interval);
      }</pre></div></div>
            
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              <p>Determine if we need to change the base url, for a pushState link
opened by a non-pushState browser.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>      <span class="keyword">this</span>.fragment = fragment;
      <span class="keyword">var</span> loc = <span class="keyword">this</span>.location;
      <span class="keyword">var</span> atRoot = loc.pathname.replace(<span class="regexp">/[^\/]$/</span>, <span class="string">'$&amp;/'</span>) === <span class="keyword">this</span>.root;</pre></div></div>
            
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              <p>Transition from hashChange to pushState or vice versa if both are
requested.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>      <span class="keyword">if</span> (<span class="keyword">this</span>._wantsHashChange &amp;&amp; <span class="keyword">this</span>._wantsPushState) {</pre></div></div>
            
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              <p>If we&#39;ve started off with a route from a <code>pushState</code>-enabled
browser, but we&#39;re currently in a browser that doesn&#39;t support it...</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>        <span class="keyword">if</span> (!<span class="keyword">this</span>._hasPushState &amp;&amp; !atRoot) {
          <span class="keyword">this</span>.fragment = <span class="keyword">this</span>.getFragment(<span class="literal">null</span>, <span class="literal">true</span>);
          <span class="keyword">this</span>.location.replace(<span class="keyword">this</span>.root + <span class="keyword">this</span>.location.search + <span class="string">'#'</span> + <span class="keyword">this</span>.fragment);</pre></div></div>
            
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              <p>Return immediately as browser will do redirect to new url</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>          <span class="keyword">return</span> <span class="literal">true</span>;</pre></div></div>
            
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              <p>Or if we&#39;ve started out with a hash-based route, but we&#39;re currently
in a browser where it could be <code>pushState</code>-based instead...</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>        } <span class="keyword">else</span> <span class="keyword">if</span> (<span class="keyword">this</span>._hasPushState &amp;&amp; atRoot &amp;&amp; loc.hash) {
          <span class="keyword">this</span>.fragment = <span class="keyword">this</span>.getHash().replace(routeStripper, <span class="string">''</span>);
          <span class="keyword">this</span>.history.replaceState({}, document.title, <span class="keyword">this</span>.root + <span class="keyword">this</span>.fragment + loc.search);
        }

      }

      <span class="keyword">if</span> (!<span class="keyword">this</span>.options.silent) <span class="keyword">return</span> <span class="keyword">this</span>.loadUrl();
    },</pre></div></div>
            
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              <p>Disable Backbone.history, perhaps temporarily. Not useful in a real app,
but possibly useful for unit testing Routers.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    stop: <span class="keyword">function</span>() {
      Backbone.$(window).off(<span class="string">'popstate'</span>, <span class="keyword">this</span>.checkUrl).off(<span class="string">'hashchange'</span>, <span class="keyword">this</span>.checkUrl);
      clearInterval(<span class="keyword">this</span>._checkUrlInterval);
      History.started = <span class="literal">false</span>;
    },</pre></div></div>
            
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              <p>Add a route to be tested when the fragment changes. Routes added later
may override previous routes.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    route: <span class="keyword">function</span>(route, callback) {
      <span class="keyword">this</span>.handlers.unshift({route: route, callback: callback});
    },</pre></div></div>
            
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              <p>Checks the current URL to see if it has changed, and if it has,
calls <code>loadUrl</code>, normalizing across the hidden iframe.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    checkUrl: <span class="keyword">function</span>(e) {
      <span class="keyword">var</span> current = <span class="keyword">this</span>.getFragment();
      <span class="keyword">if</span> (current === <span class="keyword">this</span>.fragment &amp;&amp; <span class="keyword">this</span>.iframe) {
        current = <span class="keyword">this</span>.getFragment(<span class="keyword">this</span>.getHash(<span class="keyword">this</span>.iframe));
      }
      <span class="keyword">if</span> (current === <span class="keyword">this</span>.fragment) <span class="keyword">return</span> <span class="literal">false</span>;
      <span class="keyword">if</span> (<span class="keyword">this</span>.iframe) <span class="keyword">this</span>.navigate(current);
      <span class="keyword">this</span>.loadUrl();
    },</pre></div></div>
            
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              <p>Attempt to load the current URL fragment. If a route succeeds with a
match, returns <code>true</code>. If no defined routes matches the fragment,
returns <code>false</code>.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    loadUrl: <span class="keyword">function</span>(fragment) {
      fragment = <span class="keyword">this</span>.fragment = <span class="keyword">this</span>.getFragment(fragment);
      <span class="keyword">return</span> _.any(<span class="keyword">this</span>.handlers, <span class="keyword">function</span>(handler) {
        <span class="keyword">if</span> (handler.route.test(fragment)) {
          handler.callback(fragment);
          <span class="keyword">return</span> <span class="literal">true</span>;
        }
      });
    },</pre></div></div>
            
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              <p>Save a fragment into the hash history, or replace the URL state if the
&#39;replace&#39; option is passed. You are responsible for properly URL-encoding
the fragment in advance.</p>
<p>The options object can contain <code>trigger: true</code> if you wish to have the
route callback be fired (not usually desirable), or <code>replace: true</code>, if
you wish to modify the current URL without adding an entry to the history.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    navigate: <span class="keyword">function</span>(fragment, options) {
      <span class="keyword">if</span> (!History.started) <span class="keyword">return</span> <span class="literal">false</span>;
      <span class="keyword">if</span> (!options || options === <span class="literal">true</span>) options = {trigger: !!options};

      <span class="keyword">var</span> url = <span class="keyword">this</span>.root + (fragment = <span class="keyword">this</span>.getFragment(fragment || <span class="string">''</span>));</pre></div></div>
            
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              <p>Strip the fragment of the query and hash for matching.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>      fragment = fragment.replace(pathStripper, <span class="string">''</span>);

      <span class="keyword">if</span> (<span class="keyword">this</span>.fragment === fragment) <span class="keyword">return</span>;
      <span class="keyword">this</span>.fragment = fragment;</pre></div></div>
            
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              <p>Don&#39;t include a trailing slash on the root.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>      <span class="keyword">if</span> (fragment === <span class="string">''</span> &amp;&amp; url !== <span class="string">'/'</span>) url = url.slice(<span class="number">0</span>, -<span class="number">1</span>);</pre></div></div>
            
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              <p>If pushState is available, we use it to set the fragment as a real URL.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>      <span class="keyword">if</span> (<span class="keyword">this</span>._hasPushState) {
        <span class="keyword">this</span>.history[options.replace ? <span class="string">'replaceState'</span> : <span class="string">'pushState'</span>]({}, document.title, url);</pre></div></div>
            
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              <p>If hash changes haven&#39;t been explicitly disabled, update the hash
fragment to store history.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>      } <span class="keyword">else</span> <span class="keyword">if</span> (<span class="keyword">this</span>._wantsHashChange) {
        <span class="keyword">this</span>._updateHash(<span class="keyword">this</span>.location, fragment, options.replace);
        <span class="keyword">if</span> (<span class="keyword">this</span>.iframe &amp;&amp; (fragment !== <span class="keyword">this</span>.getFragment(<span class="keyword">this</span>.getHash(<span class="keyword">this</span>.iframe)))) {</pre></div></div>
            
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        <li id="section-184">
            <div class="annotation">
              
              <div class="pilwrap ">
                <a class="pilcrow" href="#section-184">&#182;</a>
              </div>
              <p>Opening and closing the iframe tricks IE7 and earlier to push a
history entry on hash-tag change.  When replace is true, we don&#39;t
want this.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>          <span class="keyword">if</span>(!options.replace) <span class="keyword">this</span>.iframe.document.open().close();
          <span class="keyword">this</span>._updateHash(<span class="keyword">this</span>.iframe.location, fragment, options.replace);
        }</pre></div></div>
            
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              </div>
              <p>If you&#39;ve told us that you explicitly don&#39;t want fallback hashchange-
based history, then <code>navigate</code> becomes a page refresh.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>      } <span class="keyword">else</span> {
        <span class="keyword">return</span> <span class="keyword">this</span>.location.assign(url);
      }
      <span class="keyword">if</span> (options.trigger) <span class="keyword">return</span> <span class="keyword">this</span>.loadUrl(fragment);
    },</pre></div></div>
            
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              <p>Update the hash location, either replacing the current entry, or adding
a new one to the browser history.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    _updateHash: <span class="keyword">function</span>(location, fragment, replace) {
      <span class="keyword">if</span> (replace) {
        <span class="keyword">var</span> href = location.href.replace(<span class="regexp">/(javascript:|#).*$/</span>, <span class="string">''</span>);
        location.replace(href + <span class="string">'#'</span> + fragment);
      } <span class="keyword">else</span> {</pre></div></div>
            
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              </div>
              <p>Some browsers require that <code>hash</code> contains a leading #.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>        location.hash = <span class="string">'#'</span> + fragment;
      }
    }

  });</pre></div></div>
            
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        <li id="section-188">
            <div class="annotation">
              
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              </div>
              <p>Create the default Backbone.history.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>  Backbone.history = <span class="keyword">new</span> History;</pre></div></div>
            
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        <li id="section-189">
            <div class="annotation">
              
              <div class="pilwrap for-h2">
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              </div>
              <h2>Helpers</h2>

            </div>
            
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        <li id="section-190">
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              <p>Helper function to correctly set up the prototype chain, for subclasses.
Similar to <code>goog.inherits</code>, but uses a hash of prototype properties and
class properties to be extended.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>  <span class="keyword">var</span> extend = <span class="keyword">function</span>(protoProps, staticProps) {
    <span class="keyword">var</span> parent = <span class="keyword">this</span>;
    <span class="keyword">var</span> child;</pre></div></div>
            
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              </div>
              <p>The constructor function for the new subclass is either defined by you
(the &quot;constructor&quot; property in your <code>extend</code> definition), or defaulted
by us to simply call the parent&#39;s constructor.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    <span class="keyword">if</span> (protoProps &amp;&amp; _.has(protoProps, <span class="string">'constructor'</span>)) {
      child = protoProps.constructor;
    } <span class="keyword">else</span> {
      child = <span class="keyword">function</span>(){ <span class="keyword">return</span> parent.apply(<span class="keyword">this</span>, arguments); };
    }</pre></div></div>
            
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        <li id="section-192">
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              </div>
              <p>Add static properties to the constructor function, if supplied.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    _.extend(child, parent, staticProps);</pre></div></div>
            
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              </div>
              <p>Set the prototype chain to inherit from <code>parent</code>, without calling
<code>parent</code>&#39;s constructor function.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    <span class="keyword">var</span> Surrogate = <span class="keyword">function</span>(){ <span class="keyword">this</span>.constructor = child; };
    Surrogate.prototype = parent.prototype;
    child.prototype = <span class="keyword">new</span> Surrogate;</pre></div></div>
            
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        <li id="section-194">
            <div class="annotation">
              
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                <a class="pilcrow" href="#section-194">&#182;</a>
              </div>
              <p>Add prototype properties (instance properties) to the subclass,
if supplied.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    <span class="keyword">if</span> (protoProps) _.extend(child.prototype, protoProps);</pre></div></div>
            
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        <li id="section-195">
            <div class="annotation">
              
              <div class="pilwrap ">
                <a class="pilcrow" href="#section-195">&#182;</a>
              </div>
              <p>Set a convenience property in case the parent&#39;s prototype is needed
later.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>    child.__super__ = parent.prototype;

    <span class="keyword">return</span> child;
  };</pre></div></div>
            
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        <li id="section-196">
            <div class="annotation">
              
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              </div>
              <p>Set up inheritance for the model, collection, router, view and history.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>  Model.extend = Collection.extend = Router.extend = View.extend = History.extend = extend;</pre></div></div>
            
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        <li id="section-197">
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              </div>
              <p>Throw an error when a URL is needed, and none is supplied.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>  <span class="keyword">var</span> urlError = <span class="keyword">function</span>() {
    <span class="keyword">throw</span> <span class="keyword">new</span> Error(<span class="string">'A "url" property or function must be specified'</span>);
  };</pre></div></div>
            
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        <li id="section-198">
            <div class="annotation">
              
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              </div>
              <p>Wrap an optional error callback with a fallback error event.</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>  <span class="keyword">var</span> wrapError = <span class="keyword">function</span>(model, options) {
    <span class="keyword">var</span> error = options.error;
    options.error = <span class="keyword">function</span>(resp) {
      <span class="keyword">if</span> (error) error(model, resp, options);
      model.trigger(<span class="string">'error'</span>, model, resp, options);
    };
  };

}).call(<span class="keyword">this</span>);</pre></div></div>
            
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    </ul>
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